Air conditioning system for railway cars



March 19, 1940. M. P. wlNTHER' `AIll CONDITIONING SYSTEI FOR RAILWAYCARS Wmv Filed lay 23, 1934 Patented Mar. 19, 1940 UNITED s'rli'riszsPATENT OFFICE Martin P. Winther, Waukegan, Ill., assignor toPullman-Standard Car Manufacturing Company, Chicago, Ill., a corporationof Delaware Application May 23, 1934, Serial No. 727,149

17 Claims.

Railway cars are often required to lay over at stations to awaitconnecting trains and any practical system of passenger car airconditioning must be capable of furnishing properly conditioned airduring such periods. A similar problem is presented when a train isascending a long grade and the speed of the train is insufficient tofurnish the necessary power for operating the air conditioning system.

The problem is usually met by equipping the air conditioned cars withauxiliary generators and storage batteries so that electrical energy maybe stored for use in operating the apparatus when the car is stopped, orwhen car movement Ais ins uflicient to supply the necessary energy. But

this attempted solution to the problem is expensive and adds much weightto car equipment.

,f The present invention offers a solution to the -problem by storingrefrigeration, rather than electrical energy, while the car is running.If an air conditioning system is properly designed, the refrigeratingequipment always has suflicient capacity to carry the peak load, whichin passenger car installations is approximately one-third greater thanthe normal load. Consequently the -refrigerating equipment is idle aportion of the time during normal operation, and advantage is taken ofthis fact in the system of the invention.

The principal object of the invention is to provide a completelyautomatic air conditioning system for railway carsparticularly insofaras its operation deals with the furnishing of temperature control-butother objects are to reduce weight, conserve power, avoid bulk, andutilize the full capacities of the apparatus to effect these and othereconomies.

Further and other objects and advantages will appear as the disclosureproceeds, and the de- 40 `scription is read in `conjunction with theaccompanying drawing, in which Fig. 1 is a semi-diagrammatic viewshowing a preferred embodiment of the invention;v and Fig. 2 illustratesthe operation of thel ice thermostat in the fluid task. v

A preferred embodiment of the invention is shown in the drawing and willhereafter be described, but this is'for the purpose of disclosure onlyand should not be construed to impose lim- 541 itations on the appendedclaims unless required by the prior art. l

The-invention has been shown applied to a standard passenger car, orPullman, having a body lo equipped with an air duct Il adjacent to theroof. The duct preferably runs the entire length ofthe car and grillesI2, spaced apart at suitable intervals, connect the duct with thepassenger space I3.

An air conditioning chamber I4 is located overhead at one end of the carbody and contains 6 a primary coil I5 and a secondary coil IB. Acentrifugal blower I 1, which is also located overhead, draws air fromthe car vestibule I8 through a grille I9 and from the passenger space I3through a grille 20 and forces the air through the l0 coils I5 and I6into the duct II where the air is distributed throughout the passengerspace. Preferably, a lter 2| is interposed between the fresh air intakeI9 and the blower I1, and this lter may be either of the mechanicaltype, or it 5 may consist of a Water spray.

As this invention is more particularly concerned with the means foradding and removing heat units from the current of air which is passedinto the car than it is with the particular system of air distributionand its method of control, no attempt will be made to discuss thecontrol of the air movement, or the many possible variations from thearrangement shown in the draw- 25 ing.

Sufiice it to say that the grilles I9 and 20 may be provided withsuitable dampers for controlling the proportion of fresh andre-circulated air, and these may be controlled in any well :lo knownmanner. Also, the air conditioning chain: ber I4 may be equipped withhumidifying apparatus and any other apparatus which is common toinstallations of this character. The invention is in no way limited tothe details of the 35 air distribution system.

Principal elements of the air conditioning system; and their generalorganization In the system of this invention, the air passing 40 throughthe conditioning chamber I4 is cooled by the direct expansion ofrefrigerant within the primary coil I5 as long vas the temperature ofthe air within the passenger space is above a predetermined maximum andprovided the car is op- 45 erating above a predetermined minimum speed.When a suilicient lowering of the temperature within the car has beenobtained, the system automatically operates to store refrigeration in afluid tank located preferably beneath the car 50 body, The fluid'tankcontains a solution having a low freezing point, a mixture of water and10% ethylene glycol having been found satisfactory. The storing ofrefrigeration in the fluid tank continues until a given amount ofrefrigerally indicated at 35.

eration has .beenkaccumulated and then the refrigerating apparatus shutsdown. y

If, in the meantime, the speed of the car drops below the predeterminedminimum, so that the refrigerating apparatus cannot maintain the propersuction pressure within the direct expansion coil l5, the cold liquidwithin the fluid tank is circulated through the coil 06 and thuscontinues to cool the air which is being forced into the car interior.

The refrigerating apparatus comprises a compressor 22 which dischargesthrough a pipe 23 into a condenser 2t where the refrigerant is liqueed.From there, the refrigerant passes through a pipe 25 into a liquidreceiver 26 and thence through a pipe 2l to an expansion valve 2t whichpermits the refrigerant to expand into the coil .l5 at a given suctionpressure. The expanded gas is returned to the compressor through a pipe29.

The compressor, condenser and liquid receiver are preferably locatedbeneath thecar body and are arranged so that the natural draft from carmovement will to a certain extent keep them cool. Fans, however, areemployed where necessary, as for example a condenser ian 3l?.

The compressor is driven directly from the car axle through anelectro-magnetic clutch gen- The clutch consists of a quill shaft 3Sjournalled in a housing Sland having one end equipped with iield coils38 which coact with a cup-shaped armature 39 driven from the caraxle d@through a gear box il and shaft d2. The armature 39 always revolves atarate proportional to car speed and the extent of energization of theiield coils 33 determines the rate of rotation of the quill shaft Therear end of the quill shaft is equipped with pulleys i3 and it fordriving the compressor and condenser ian respectively.

A generator bil supplies the necessary electrical 'energy for theoperation of the air conditioning system and is driven by a belt 5l fromthe shaft 12. It, of course, may be operated from another car axle ifdesired.

A battery 52 is arranged to ioat on the generator 5U to provide theelectrical requirements of certain parts of the apparatus when the caris stopped, or is travelling below a predetermined minimum speed.

The iuid tank 53 isa part of a closed fluid circuit which includes pipes54, the secondary coil l@ and pipe 55. rlhe latter pipe enters the iiuidtank and discharges the uid which it carries through small orifices 55.

Circulation of uid through the circuit is ei'- fected by a fluid pump5l.

Within the fluid tank 53 is an evaporator coil 5l, an ice thermostat 58,a steam coil 5S, and a hot water thermostat tti. The evaporator coil 57is connected in parallel with the primary coil l5 through pipes El andt2 which connect with the pipes 2l and 29, respectively. An expansionvalve t3 is interposed between the pipe 6i and the evaporator coil 5l toregulate the pressure at which the refrigerant is expanded into the coil5i.

A cooling thermostat and a heating thermostat Sf, both of which arelocated within the passenger space, control the operation oi' thesystem, and aj hand switch lil initially determines which of the two-thermostats is operative.

For convenience of description, the electrical circuits will be groupedunder the headings of control circuits, cooling circuits and heatingcircuits and light, medium and heavy lines have aiesse been used in thedrawing for distingushing the three groups of circuits, respectively.

Control circuits control regulator l2, a compressor switch 13, and l astandby relay lll.

lThe battery cut-in switch lll disconnects the battery from thegenerator when the car speed is such that the generator output is lessthan the battery voltage. The circuit which controls this switchincludes conductors lli, lll, solenoid lil, and conductors i9 and B.

The generator regulator increases the resistance in the generator fieldas the car speed increases so4 that the output of the generatorqismaintained within desired limits; The regulator includes a carbon pileill which is in series with the generator i'ield S2, the latter beingconnected across the generator armature l5. Pressure on the carbon pileis automatically decreased .i as car speed increases, by a solenoid 84connected across the generator armature l5.

The speed control regulator 'l2 is Very similar to the generatorregulator and consists of a carbon pile t to which pressure is variablyapplied by a solenoid 86 connected by conductors 8l, 88, t@ and 9i]across the generator armature. It will be observed that the compressorswitch i3 is in series with this circuit.

The purpose of the speed control regulator is to increase the resistancein the circuit through the eld coils 38, of the electromagnetic clutchas the car speed becomes greater so that the .current through the coils38 is reduced and, as

a consequence, more slippage is effected in the clutch. In this way, thespeed of the compressor is maintained within reasonable limits.

The compressor switch 713 cuts out the electromagnetic clutch until thecar speed is above a certain minimum, so that the compressor will notconstitute a drag on the car at low speeds when friction losses arehigh. The compressor 'switch 73 may be eliminated, of course, under somecircumstances, but it is particularly desirable when an electric motoris substituted for the electro-magnetic clutch 35 to drive thecornpressor 22.

The solenoid 9i of the compressor switch is connected across thegenerator armature by conductors T16, 92 and Bil.

The standby switch 'M places the fluid pump 5i in operation when the caris stopped, or travelling at low speeds. Otherwise, it places thegenerator and battery in series with the cooling thermostat t5 and aselector relay 93.

The generator, it will be observed, is connected to the battery throughconductors gli and conductors titi, i9, switch armature 95, conductors96, ill and 93.

Cooling circuits lt has already been stated that the primary coil l5 isin operation as long as the car is operating above the predeterminedminimum speed, and there is need for air cooling.

Let us assume now that the car speed is maintained, but that the coolingthermostat is.

opened, due to the air in the car having a sufficiently low temperature.

The compressor 22 is then made to supply refrigerant to the evaporatorcoil 5l at a pressure of say 18 lbs. which, for a refrigerant such asFreon (dichlorodifluoromethane), would' correspond to a temperature ofaround 10 or 15 above zero Fahrenheit. This pressure and temperaturecompares with a temperature of F.. and approximately lbs. pressure inthe coil i5 when it is in operation.

The low temperature of the refrigerant in the coil 51 causes ice to formupon the pipes as the temperature of the fiuid within the tank graduallydiminishes and finally a suicient quantity of ice is built up on thepipes to encase the ice thermostat 58 (see Fig. 2). At the moment whenthis occurs, the heat sensitive element in the thermostat 58 (which maybe of any suitable form) moves quickly due to the fact that until thethermostat is surrounded by ice, a portion of it is exposed to thecirculating iiuid which may have a temperature of around 30 F., whereasthe ice has a much lower temperature. As soon a's the ice surrounds thethermostat, it insulates the thermostat from the higher temperature ofthe iiuid and this sudden drop in temperature is recorded by thethermostat and operates to shut o the compressor motor.

Whenever the car speed falls below the predetermined minimum, the fluidpump 51 is automatically started and as the circulation or" fluidcontinues, the ice is slowly melted from the evaporator coil 51 so thatthe temperature oi the uid is maintained at thedesired low temperature.

In considering the cooling circuits, let us rst assume that the car isstopped, or is moving below a predetermined minimum speed and refrigeration has been stored in the uid tank by previous operation of thecar. In such a case, the standby relay 14 is de-energized and thearmature |05 closes the contacts |06 and |01. connects the battery 52with the uid pump 51 through conductors |08, |09, |10, HI, H2 and S8. Itwill be observed that the cooling thermostat S5 is also in this circuitso that the iiuid. pump is stopped whenever there is no need for furtherair cooling.

Now let it be assumed that the car is moving above the predeterminedminimum speed, and the thermostat 65 calls for cooling. In such a case,the standby relayr14 is energized, and the armature |05 bridges thecontacts ||4 and |15; the selector relay 93 is also energized, and thecontacts ||6 and ||1 are bridged; the shut-off valve ||8 in therefrigerant pipe 21 is open (the valve automatically closing wheneverthe circuitis broken); and the compressor switch 13 is closed. Thislatter switch places the electromagnetic clutch in operation and itscircuit can be traced from the positive side of the generator armature15, through conductor 81, compressor switch 13, conductor I I9 to acommutator on the quill shaft 36, thence through the eld coil 38, areturn commutator, conductor |20, speed control regulator 12 through thecontacts ||1 and ||6 which are bridged by the armature of the selectorrelay, thence through conductor |2| to conductor 96, switch armature 95of the battery cut-in switch, conductors 19 and 80, back to the This 51from the compressor when the primary coil l5 is in operation in order toprevent refrigerant from condensing in the latter coil, and this isaccomplished by electro-magnetic shut-off valves |25 and |26 interposedin the refrigerant lines 6| and 62, respective1y.` These valves areclosed whenever the circuit through the valves is open.

As soon as the temperature within the car has been lowered a suicientamount under the conditions last stated, the thermostat E5 opens and thecircuit through the selector relay 03 and the shut-01T valve H8 isbroken. The refrigerant line 21 is thus closed and the selector relayarmature is lifted by a spring |21 or equivalent means to bridgethe'contacts |28 and 29. With these contacts bridged, a shunt circuitcan be traced from the conductor 05 in the speed control circuit throughconductor H30, contacts l2@ and d20, conductor 53|, through the shut-ofivalves |25, |25, leading to the evaporator coil 5l, thence throughconductor 132 to conductor l2| and thence back to the negative side ofthe armature "l5 through conductors 95, armature 95 of the batterycut-in, and conductors 19 and 20.

This last mentioned shunt circuit when energized by Connecting thecontacts 120 and 129 opens the shut-off valves |25 and i225 and placesthe evaporator coil 51 in operative connection with the compressor 22while at the same time shut-olf valve l i8 is closed in the refrigerantline leading to the primary coil l5.

It will be observed that the de-energization of the selector relay 93does not itself open the circuit through the electro-magnetic clutch 35because a shunt circuit is provided which includes a relay |33 operatedin response to the ice thermostat 58. This shunt circuit is connectedacross the contacts H5 and ||1' and may be traced through conductors |34and |35. Hence the electro-magnetic clutch 35 operates as long as eitherthe primary coil l5 or the evaporator coil 51 require the compressor 22to be running.

Instead of using an electro-magnetic clutch in driving the compressordirectly from the car axle, it is possible to employ an electric motorhaving its terminals connected across the conductors ||9 and |20 at thepoint where they are shown connected to 'the commutators of the clutch35. The compressor switch 13 would be essential in such a case if it isintended that the compressor be idle when the car is standing, ortravelling below a given speed. Of course, if large batteries are used,the switch 13 could be omitted.

Heating circuits When the manual switch 61 is moved upwardly in Fig. 1,it bridges two contacts which places the heating system in operation.

'Ihe steam coil 59 in the tank 53 is adapted to be fed through a pipe|40 which connects with a steam valve |4| automatically controlled by asolenoid |42 in series with the heating thermostat 65. The circuitcontrolling the operation of the valve can be traced from the positiveside of the battery and generator through conductors |08 and |43 to thesolenoid |42, thence through conductor |44 to the heating thermostat andthence through the switch 61 and conductors ||2 and 98, back to thenegative side of the battery and generator. When the heating thermostatis closed, the steam valve is on, as can readily be seen from thedrawing.

The uid pump 51 is adapted to function as long as the hand switch El'calls for heatingunless the hot Water thermostat @il which controls theoperation of an electro-magnetic relay |45 indicates that thetemperature of the fluid is below a predetermined amount, for example110 F. The manner in which this function is accomplished is readilyunderstood by observing that the circuit which controls the fluid pumpis in series with the thermostatic relay H5, but does not include theheating thermostat 65. The circuit can be traced from the positive sideof the battery and generator through conductors 18,146, thermostaticrelay M5, conductors Ml and lll, thence through the uid pump 57,conductor lill, conductor M8 and back to the negative side of thebattery and generator through the handswitch 6l,conductors l l2 and 9d.

The steam' coil 59 is thus intermittently operated yin accordance withthe demands of the heating thermostat while the fluid pump iscontinuously operated unless Vthe temperature of the fluid should forsome reason fall below a predetermined minimum."

The primary coil l5 is in reality a direct expansion coil since therefrigerant is permitted to expand directly into the coil. The secondarycoil I6 is ordinarily termed an indirect expansion coil due to the factthat the fluid which circulates through it is a secondary refrigerant,

\ i. e. it is cooled by a primary refrigerant, which in this case iscirculated through the evaporator coil 5l.

The vinvention may be variously embodied within the scope of theappended claims.

What I claim, therefore, is:

1. In combination with a passenger car, means for forcing a current ofair into the car, primary and secondary coils in the path of the air,

- a fluid circuit including the secondary coil, an

evaporator coil in the fluid circuit connected in parallel with theprimary coil, refrigerating apparatus adapted to supply refrigerant toeither the primary or the evaporator coil, means for circulating the uidin said circuit and means responsive to the temperature Within the carfor determining which coil is to receive refrigerant from the apparatus.

2. In combination with a passenger car, means for forcing a current ofair into the car, primary and secondarycoils in the path of the air, afluid circuit including the secondary coil, an evaporator coil in thefluid circuit connected in parallel with the primary coil, refrigeratingapparatus adapted to supply refrigerant to either the primary or theevaporator coil, and means for alternately supplying refrigerant to theprimary and evaporator coils in response to conditions within the car.

3. In combination with a passenger car, means for forcing a current ofair into the car, primary and secondary coils in the path of the air, afluid circuit including the secondary coil, an evaporator coil in thefluid circuit connected in parallel with the primary coil, refrigeratingapparatus adapted to supply refrigerant to either the primary or theevaporator coil, and means forsupplying refrigerant to the primary coilas long as cooling of the air current is required and thereafter tosupply refrigerant to the evaporator coil for reserve use.

4. In combination with a passenger car, means for forcing a current ofair into the car, primary and secondary coils in the path of the air, afluid circuit including the secondary coil, an evaporator coil in thefluid circuit connected in parallelwith the primary coil,refr'ig'erating' apparatus adapted to supply refrigerant to either theprimary or the evaporator coll, means for supplying refrigerant to theprimary coil as long as cooling of the air current is required andthereafter to supply refrigerant to the evaporator coil for reserve use,and means for rendering the refrigerating apparatus inactive when thereserve refrigeratlonreaches a predetermined amount.

5. In combination with a passenger car, means for forcing a current ofair into the car, primary and secondary coils in the path of the air, afluid circuit including the secondary coil, an evaporator coil in theuid circuit connected in parallel with the primary coil, refrigeratingapparatus adapted to supply refrigerant to either the primary or theevaporator coil, an electrically operated drive for the refrigeratingapparatus, and means for maintaining the drive in operation as long aseither 'the primary coil or the evaporator coil require refrigerationaccording to predetermined conditions.

6. In combination with a passenger car, means for forcing a current ofair into the car, primary and secondary coils in the path of the air, afluid circuit including the secondary coil, an evaporator coil in theiluid circuit connected in paral-l lel with the primary coil, apparatusfor supplying refrigerant to either the primary or the evaporator coilaccording t'o predetermined conditions, and means for operating theapparatus at a higher suction pressure when the primary coil is beingfed with refrigerant than when the evaporator coil is receivingrefrigerant from the apparatus.

'7. In combination with a passenger car, means for forcing a current ofair into the car, primary and secondary coils in the path of the air, afluid circuit including the secondary coil, an evaporator coil in thefluid circuit connected in parallel with the primary coil, apparatus forsupplying Erefrigerant to either the primary or the evaporator coilaccording to predetermined conditions, and means for operating theapparatus at a higher suction pressure when the primary coil is beingfed with refrigerant than when the evaporator coil is receivingrefrigerant from the appa ratus, and valve means for preventingrefrigerant from condensing in the evaporator coil when the primary coilis in operation.

8. In combination with a passenger car, means `for forcing a current ofair into the car, primary and secondary coils in the path of the airincluding a fluid medium in the latter coil, a fluid circuit includingthe secondary coil, an evaporator coil in the fluid circuit. connectedin parallel with the primary coil, apparatus adapted to supplyrefrigerant to the primary coil under predetermined conditions, and tothe evaporator coil under other conditions, and means for circulatingthe uid in said circuit.

9. In combination with a passenger car, means for forcing a current ofair into the car, primary and secondary coils in the path of the airincluding a fluid medium in the latter coil, a fluid circuit includingthe secondary coil, an evaporator coil in the fluid circuit connected inparallel with the primary coil, apparatus including a compressornormally supplying refrigerant to the primary coil at a relatively highsuction pressure when cooling of the air is required, but being adaptedto supply refrigerant to the direct expansion coil in the fluidcircuit'at a relatively low suction pressure when immediate cooling of*he air is not required.

10. The method of conditioning air under forced draft which comprisescirculating refrigerant between a liquefying zone and a firstevaporating zone located in an air conditioning zone in the path of thecirculating air, removing heat' from air to be .conditioned insaidiconditioning zone by direct evaporation of refrigerant in saidevaporating zone, circulating refrigerant between said liquefyingzoneand a second evaporating zone when refrigerant liquefaction occurs insaid liquefying zone `faster than refrigerant evaporation in said firstevaporating zone, cooling a holdover in a storage zone by evaporation ofrefrigerant in said second evaporating Zone, circulating holdover fromsaid storage zone to said air conditioning zone and there removing heatfrom air to be conditioned when refrigerant liquefaction is insufficientto cool the air.

1l. An air conditioning system for a vehicle comprising a compressor,condenser and evaporator in refrigerant circulating relationhip andassociated with said vehicle, said evaporator being located in the pathof air to be conditioned for said vehicle, means for driving saidcompressor in functional relationship to the motion of the vehicle, asecond evaporator, means for cooling a holdover with said secondevaporator, means for circulating said holdover in thermal exchangerelationship with air to be conditioned when said compressor, because ofinadequate car speed, lacks sufficient capacity to condition the air.

12. An air conditioning system for a vehicle comprising a compressor,condenser and evaporator in refrigerant circulating relationship andassociated with said vehicle, said evaporator being located in the pathof air to be conditioned for said vehicle, means for driving saidcompresser from a rotating part on the vehicle and in functionalrelationship to the motion of the vehicle, a second evaporator connectedto said condenser and compressor in thermal exchange relationship with aholdover, means causing said second evaporator to cool said holdoverwhen said compressor because of suflicient car speed and/or relativelylow heat load attains excess refrigerating capacity, and means forcirculating the holdover in thermal exchange relationship with air to beconditioned when the power for operating the compressor from saidrotating part falls below a predetermined minimum.

13. In combination with a passenger car, means for forcing a current ofair into the car, primary and secondary coils in the path of the air, auid circuit including the secondary coil, an evaporator coil in thefluid circuit connected in parallel with the primary coil, refrigeratingapparatus adapted to supply refrigerant to the primary and evaporatorcoils, means for circulating the fluid in said circuit, and meansresponsive to the temperature within the car for controlling theoperation of the refrigerating apparatus.

14. In combination with a passenger car, means for forcing a current ofair into the car, primary and secondary coils in the path of the airincluding a iiuid medium in the latter coil, apparatus for supplyingrefrigerant to the primary coil and fol` abstracting heat from the fluidmedium in vthe secondary coil, and means responsive at least in part tothe speed of the car for selecting which coil, if either, is inoperation.

l5. In combination with a passenger car, means for forcing a current ofair into the car, primary and secondary coils in the path of the air, afluid circuit including the secondary coil, an evaporator coil in theuid circuit, means for circulating the iiuid in the circuit, and meansincluding the same refrigerating apparatus for supplying refrigerant tothe primary and the evaporator coils.

16. The method of conditioning air for a Vehicle by power taken from oneof the vehicle wheels which consists in utilizing the power Whenever itexceeds a given minimum for operating refrigerating apparatus to coolair delivered by forced draft to the vehicle interior, utilizing thepower thus characterized to provide cooling of a holdover when the airin the vehicle has been sufficiently cooled, and circulating theholdover in heat exchange relation to said draft in response to a dropin said power below the predetermined minimum.

17. In an air conditioning system having a varying heat load, a hightemperature evaporator for cooling air by direct heat exchange, a lowtemperature evaporator for freezing water, means responsive toatmospheric conditions in an enclosure served by the system forselectively supplying refrigerant to said high temperature Yevaporatorduring high air conditioning load periods for cooling said air by directexpansion of the refrigerant and to said low temperature evaporatorduring low air conditioning load periods for freezing water, and meansfor utilizing the refrigerating eect of said frozen water to cool saidair when the high temperature evaporator is inoperative.

MARTIN P. W'DITHER.

